1. Field of the Invention
The present invention relates to the field of lifting devices having a boom which can be moved with respect to a frame and pivoted to various angles with respect to a horizontal plane. More particularly, this invention relates to a counterweight system wherein the counterweight has a center of gravity generates an anti-tipping moment to help prevent the lifting device from tipping over even when the boom is extended, articulated, angled and/or loaded.
2. Problems in the Art
It is well known in the art of boom operated lifting devices that such devices are prone to tip over when the boom is extended, articulated, angled and/or loaded. Often the size and weight of the machine is selected to enhance its stability. Unfortunately, such an approach lacks flexibility and promotes inefficiency in the design. Therefore, there is a need for a simple, flexible and cost efficient solution to the overturning problem.
3. Features of the Invention
A primary object of the present invention is the provision of a means for counterweighting a boom operated lifting device.
A further object of the present invention is the provision of a counterweight system that fits within the turret of the machine.
A further object of the present invention is the provision of a counterweight system wherein the center of gravity of the counterweight is offset from the pivot axis of the boom so as to create an anti-tipping moment.
A further object of the present invention is to provide a counterweight system wherein the counterweight is pivotally hung from the lower end of the boom.
A further object of the present invention is the provision of a counterweight system wherein a linkage means interconnects the boom and the counterweight so as to move the counterweight, and therefore its center of gravity, when the boom is pivoted up or down.
A further object of the present invention is a provision of a counterweight system wherein a counterweight linked to the boom has wheels and rolls along the base plate of the turret in response to the pivoting of the boom.
A further object of the present invention is the provision of a counterweight system wherein the counterweight can pivot freely to a desired angle in one direction and thereafter acts as a fixed counterweight for the further movement in that direction.
These and other objects will be apparent to one skilled in the art from the drawings, the claims, and the description which follows.